Fix miri

src/tools/miri/src/lib.rs

@@ -67,6 +67,7 @@ extern crate rustc_index;
 extern crate rustc_middle;
 extern crate rustc_session;
 extern crate rustc_span;
+extern crate rustc_symbol_mangling;
 extern crate rustc_target;
 // Linking `rustc_driver` pulls in the required  object code as the rest of the rustc crates are
 // shipped only as rmeta files.

src/tools/miri/src/shims/foreign_items.rs

@@ -7,6 +7,7 @@ use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrFlags;
 use rustc_middle::mir;
 use rustc_middle::ty;
 use rustc_span::Symbol;
+use rustc_symbol_mangling::mangle_internal_symbol;
 use rustc_target::{
     abi::{Align, Size},
     spec::abi::Abi,
@@ -135,15 +136,29 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 // Find it if it was not cached.
                 let mut instance_and_crate: Option<(ty::Instance<'_>, CrateNum)> = None;
                 helpers::iter_exported_symbols(tcx, |cnum, def_id| {
+                    if tcx.is_foreign_item(def_id) {
+                        // Skip over imports of items
+                        return Ok(());
+                    }
+
                     let attrs = tcx.codegen_fn_attrs(def_id);
+                    // FIXME use tcx.symbol_name(instance) instead
                     let symbol_name = if let Some(export_name) = attrs.export_name {
                         export_name
-                    } else if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE) {
+                    } else if attrs.flags.contains(CodegenFnAttrFlags::NO_MANGLE)
+                        || attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL)
+                    {
                         tcx.item_name(def_id)
                     } else {
                         // Skip over items without an explicitly defined symbol name.
                         return Ok(());
                     };
+                    let symbol_name =
+                        if attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL) {
+                            Symbol::intern(&mangle_internal_symbol(tcx, symbol_name.as_str()))
+                        } else {
+                            symbol_name
+                        };
                     if symbol_name == link_name {
                         if let Some((original_instance, original_cnum)) = instance_and_crate {
                             // Make sure we are consistent wrt what is 'first' and 'second'.
@@ -455,7 +470,9 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
 
             // Rust allocation
-            "__rust_alloc" | "miri_alloc" => {
+            name if name == mangle_internal_symbol(*this.tcx, "__rust_alloc")
+                || name == "miri_alloc" =>
+            {
                 let default = |this: &mut MiriInterpCx<'tcx>| {
                     // Only call `check_shim` when `#[global_allocator]` isn't used. When that
                     // macro is used, we act like no shim exists, so that the exported function can run.
@@ -466,9 +483,8 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     this.check_rustc_alloc_request(size, align)?;
 
                     let memory_kind = match link_name.as_str() {
-                        "__rust_alloc" => MiriMemoryKind::Rust,
                         "miri_alloc" => MiriMemoryKind::Miri,
-                        _ => unreachable!(),
+                        _ => MiriMemoryKind::Rust,
                     };
 
                     let ptr = this.allocate_ptr(
@@ -481,15 +497,14 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 };
 
                 match link_name.as_str() {
-                    "__rust_alloc" => return this.emulate_allocator(default),
                     "miri_alloc" => {
                         default(this)?;
                         return Ok(EmulateItemResult::NeedsReturn);
                     }
-                    _ => unreachable!(),
+                    _ => return this.emulate_allocator(default),
                 }
             }
-            "__rust_alloc_zeroed" => {
+            name if name == mangle_internal_symbol(*this.tcx, "__rust_alloc_zeroed") => {
                 return this.emulate_allocator(|this| {
                     // See the comment for `__rust_alloc` why `check_shim` is only called in the
                     // default case.
@@ -514,7 +529,9 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     this.write_pointer(ptr, dest)
                 });
             }
-            "__rust_dealloc" | "miri_dealloc" => {
+            name if name == mangle_internal_symbol(*this.tcx, "__rust_dealloc")
+                || name == "miri_dealloc" =>
+            {
                 let default = |this: &mut MiriInterpCx<'tcx>| {
                     // See the comment for `__rust_alloc` why `check_shim` is only called in the
                     // default case.
@@ -525,9 +542,8 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     let align = this.read_target_usize(align)?;
 
                     let memory_kind = match link_name.as_str() {
-                        "__rust_dealloc" => MiriMemoryKind::Rust,
                         "miri_dealloc" => MiriMemoryKind::Miri,
-                        _ => unreachable!(),
+                        _ => MiriMemoryKind::Rust,
                     };
 
                     // No need to check old_size/align; we anyway check that they match the allocation.
@@ -539,17 +555,14 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 };
 
                 match link_name.as_str() {
-                    "__rust_dealloc" => {
-                        return this.emulate_allocator(default);
-                    }
                     "miri_dealloc" => {
                         default(this)?;
                         return Ok(EmulateItemResult::NeedsReturn);
                     }
-                    _ => unreachable!(),
+                    _ => return this.emulate_allocator(default),
                 }
             }
-            "__rust_realloc" => {
+            name if name == mangle_internal_symbol(*this.tcx, "__rust_realloc") => {
                 return this.emulate_allocator(|this| {
                     // See the comment for `__rust_alloc` why `check_shim` is only called in the
                     // default case.

src/tools/miri/tests/pass/function_calls/exported_symbol.rs

@@ -40,6 +40,7 @@ fn main() {
 
         extern "Rust" {
             fn bar() -> i32;
+            #[rustc_std_internal_symbol]
             fn baz() -> i32;
             fn qux() -> i32;
         }
@@ -63,6 +64,7 @@ fn main() {
 
             extern "C" {
                 fn bar() -> i32;
+                #[rustc_std_internal_symbol]
                 fn baz() -> i32;
                 fn qux() -> i32;
             }